with columns and rows along with defined data types. The most common are Relational Database Management Systems (RDBMS) that are capable of handling large volumes of data such as Oracle, IBM Db2, Microsoft SQL Server, Sybase, and Teradata. The structured data domain also includes spreadsheets (not all spreadsheets contain structured data, but those that have data organized in database-like tables), desktop databases like FileMaker Pro and Microsoft Access, structured flat files, XML files, data marts, data warehouses, etc. Audio Voicemail is often discoverable under electronic discovery rules. Employers may have a duty to retain voicemail if there is an anticipation of litigation involving that employee. Data from voice assistants like Amazon Alexa and Siri have been used in criminal cases. Reporting formats Although petrifying documents to static image formats (TIFF & JPEG) had become the standard document review method for almost two decades, native format review has increased in popularity as a method for document review since around 2004. Because it requires the review of documents in their original file formats, applications and toolkits capable of opening multiple file formats have also become popular. This is also true in the ECM (Enterprise Content Management) storage markets which are converging quickly with ESI technologies. Petrification involves the conversion of native files into an image format that does not require use of the native applications. This is useful in the redaction of privileged or sensitive information, since redaction tools for images are traditionally more mature, and easier to apply on uniform image types by non-technical people. Efforts to redact similarly petrified PDF files by incompetent personnel have resulted in the removal of redacted layers and exposure of redacted information, such as social security numbers and other private information. Traditionally, electronic discovery vendors had been contracted to convert native files into TIFF images (for example 10 images for a 10-page Microsoft Word document) with a load file for use in image-based discovery review database applications. Increasingly, database review applications have embedded native file viewers with TIFF-capabilities. With both native and image file capabilities, it could either increase or decrease the total necessary storage, since there may be multiple formats and files associated with each individual native file. Deployment, storage, and best practices are becoming especially critical and necessary to maintain cost-effective strategies. Structured data are most often produced in delimited text format. When the number of tables subject to discovery is large or